Objectives: To measure in vivo three-dimensional kinematics of the mandible and associated end-point trajectories and to quantify their relationships during temporomandibular joint activities using 3D fluoroscopy. Methods: A novel fluoroscopy-based 3D measurement method was used to measure motions of the mandible and the associated end points (i.e. incisors and lateral poles of both condyles) during open close, lateral gliding and protrusion-retraction movements in healthy young individuals. The contributions of each of the rotational and translational components of the mandible to the end-point trajectories were quantified through experiment-based computer simulations. Results: The mandibular rotation was found to account for 91% of the maximal mouth-opening-capacity and 73% of the maximal lateral incisor movement, while the condylar translation contributed to 99% of the anterior protrusion distance. Incisor trajectories were nearly vertical within the first 60% of the maximal opening during the open-close movement. Conclusions: Similar condylar downward rotation paths but with bilaterally asymmetrical ranges were used to perform basic mandibular movements of different targeted TI trajectories in three dimensions, that is, open-close, lateral-gliding and protrusion-retraction. Mandibular rotations contributed to the majority of the principal displacement components of the incisor, that is, vertical during open-close and towards the working-side-during lateral-gliding, while mandibular translation contributed mainly to the forward movement of the incisor during protrusion-retraction. Owing to the anatomical constraints, the freedom of mandibular translation is limited and mainly in the anteroposterior direction, which is considered helpful for the control and stability of the TMJ during oral activities.
We are reporting on an experimental investigation of a movable diffuse reflectance spectroscopy system to extract diagnostically relevant optical properties of two-layered tissue phantoms simulating mucosae that are covered with stratified squamous epithelium. The reflectance spectra were measured at multiple sourcedetector separations using two imaging fiber bundles in contact with the phantoms, one with its optical axis perpendicular to the sample surface (perpendicular probe) and the other with its distal end beveled and optical axis tilted at 45 deg (oblique probe). Polystyrene microspheres and purified human hemoglobin were used to make tissue phantoms whose scattering and absorption properties could be well controlled and theoretically predicted. Monte Carlo simulations were used to predict the reflectance spectra for system calibration and an iterative curve fitting that simultaneously extracted the top layer reduced scattering coefficient, thickness, bottom layer reduced scattering coefficient, and hemoglobin concentration of the phantoms. The errors of the recovered parameters ranged from 7% to 20%. The oblique probe showed higher accuracy in the extracted top layer reduced scattering coefficient and thickness than the perpendicular probe. The developed system and data analysis methods provide a feasible tool to quantify the optical properties in vivo.
This study examined the innovation ability and business performance of global companies in the aerospace and defense (A&D) industry by using dynamic data envelopment analysis and ranking methods with the DuPont model. Results indicated that compared with business performance, A&D companies exhibit lower scores and higher standard deviations in the innovation ability, which signified that they should first work on reducing the gap in the level of innovation ability. DuPont analysis indicated that typical A&D companies exhibit the highest ROE. Finally, this study offers managers and policymakers detailed insights into potential areas of improvements in innovations, business performance, and profitability.
An iterative curve fitting method has been applied in both simulation [J. Biomed. Opt.17, 107003 (2012)JBOPFO1083-366810.1117/1.JBO.17.10.107003] and phantom [J. Biomed. Opt.19, 077002 (2014)JBOPFO1083-366810.1117/1.JBO.19.7.077002] studies to accurately extract optical properties and the top layer thickness of a two-layered superficial tissue model from diffuse reflectance spectroscopy (DRS) data. This paper describes a hybrid two-step parameter estimation procedure to address two main issues of the previous method, including (1) high computational intensity and (2) converging to local minima. The parameter estimation procedure contained a novel initial estimation step to obtain an initial guess, which was used by a subsequent iterative fitting step to optimize the parameter estimation. A lookup table was used in both steps to quickly obtain reflectance spectra and reduce computational intensity. On simulated DRS data, the proposed parameter estimation procedure achieved high estimation accuracy and a 95% reduction of computational time compared to previous studies. Furthermore, the proposed initial estimation step led to better convergence of the following fitting step. Strategies used in the proposed procedure could benefit both the modeling and experimental data processing of not only DRS but also related approaches such as near-infrared spectroscopy.
This study aims to evaluate the cargo and eco-efficiencies of international container shipping companies (CSCs) for the period 2013-2017 for benchmarking purposes. An integration of two-stage network directional distance function and networkbased approach in data envelopment analysis is utilized to distinguish the efficient operators. Results show that most CSCs are highly ranked in the cargo efficiency stage but lowly ranked in the eco-efficiency stage and vice versa. This study emphasizes the strengths and weaknesses of each factor of every CSC. Results can help the inefficient CSCs find the areas for improvement by learning from their peers.
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